/*
 * Copyright (c) 2016 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr.h>
#include <device.h>
#include <devicetree.h>
#include <drivers/gpio.h>
#include <nrfx_timer.h>

/* 1000 msec = 1 sec */
#define SLEEP_TIME_MS   1000

/* The devicetree node identifier for the "led0" alias. */
#define LED0_NODE DT_ALIAS(led0)

#if DT_NODE_HAS_STATUS(LED0_NODE, okay)
#define LED0	DT_GPIO_LABEL(LED0_NODE, gpios)
#define PIN	DT_GPIO_PIN(LED0_NODE, gpios)
#define FLAGS	DT_GPIO_FLAGS(LED0_NODE, gpios)
#else
/* A build error here means your board isn't set up to blink an LED. */
#error "Unsupported board: led0 devicetree alias is not defined"
#define LED0	""
#define PIN	0
#define FLAGS	0
#endif

// Get a reference to the TIMER1 instance
static const nrfx_timer_t my_timer = NRFX_TIMER_INSTANCE(4);

// Interrupt handler for the timer
// NOTE: This callback is triggered by an interrupt. Many drivers or modules in Zephyr can not be accessed directly from interrupts, 
//		 and if you need to access one of these from the timer callback it is necessary to use something like a k_work item to move execution out of the interrupt context. 
void timer1_event_handler(nrf_timer_event_t event_type, void * p_context)
{
	static int counter = 0;
	switch(event_type) {
		case NRF_TIMER_EVENT_COMPARE0:
			printk("Timer 1 callback 0. Counter = %d\n", counter++);
			break;
		case NRF_TIMER_EVENT_COMPARE1:
			printk("Timer 1 callback 1. Counter = %d\n", counter++);
			break;
		case NRF_TIMER_EVENT_COMPARE2:
			printk("Timer 1 callback 2. Counter = %d\n", counter++);
			break;
		case NRF_TIMER_EVENT_COMPARE3:
			printk("Timer 1 callback 3. Counter = %d\n", counter++);
			break;
		case NRF_TIMER_EVENT_COMPARE4:
			printk("Timer 1 callback 4. Counter = %d\n", counter++);
			break;
		case NRF_TIMER_EVENT_COMPARE5:
			printk("Timer 1 callback 5. Counter = %d\n", counter++);
			break;		
		default:
			printk("Unknown timer event!\n");
			break;
	}
}

// Function for initializing the TIMER1 peripheral using the nrfx driver
static void timer4_init(void)
{
	nrfx_timer_config_t timer_config = NRFX_TIMER_DEFAULT_CONFIG;
	timer_config.bit_width = NRF_TIMER_BIT_WIDTH_32;
	timer_config.frequency = NRF_TIMER_FREQ_1MHz;

	int err = nrfx_timer_init(&my_timer, &timer_config, timer1_event_handler);
	if (err != NRFX_SUCCESS) {
		printk("Error initializing timer: %x\n", err);
	}

	IRQ_DIRECT_CONNECT(TIMER4_IRQn, 0, nrfx_timer_4_irq_handler, 0);
	irq_enable(TIMER4_IRQn);
}

// Function for scheduling repeated callbacks from TIMER1
static void timer4_repeated_timer_start(void)
{
	nrfx_timer_enable(&my_timer);
	nrfx_timer_extended_compare(&my_timer, NRF_TIMER_CC_CHANNEL0, 500000, 
                                0, true);	
	nrfx_timer_extended_compare(&my_timer, NRF_TIMER_CC_CHANNEL1, 1000000, 
                                0, true);
	nrfx_timer_extended_compare(&my_timer, NRF_TIMER_CC_CHANNEL2, 1500000, 
                                0, true);
	nrfx_timer_extended_compare(&my_timer, NRF_TIMER_CC_CHANNEL3, 2000000, 
                                0, true);	
	nrfx_timer_extended_compare(&my_timer, NRF_TIMER_CC_CHANNEL4, 2500000, 
                                0, true);
	nrfx_timer_extended_compare(&my_timer, NRF_TIMER_CC_CHANNEL5, 3000000, 
                                0, true);
}

void main(void)
{
	const struct device *dev;
	bool led_is_on = true;
	int ret;

	dev = device_get_binding(LED0);
	if (dev == NULL) {
		return;
	}

	ret = gpio_pin_configure(dev, PIN, GPIO_OUTPUT_ACTIVE | FLAGS);
	if (ret < 0) {
		return;
	}

	// Initialize TIMER1
	timer4_init();

	timer4_repeated_timer_start();

	while (1) {
		gpio_pin_set(dev, PIN, (int)led_is_on);
		led_is_on = !led_is_on;
		k_msleep(SLEEP_TIME_MS);
	}
}